Controlling more than 95 percent of all search queries in the U.S., Google and Bing's search engines have more influence on search now than ever before. Today, inbound marketers want to know which of these two search giants drives the most user engagement in organic search results. Understanding user engagement will help digital marketers shift their focus to the most lucrative search engine. However, measuring engagement is a difficult exercise that requires a very large and very diverse data set. Fortunately, we have a large and diverse data set from our client rankings and traffic results. The results have been combined into a click-through rate study that's one of the most robust studies in the last few years, and the only one that compares data from Google and Bing. A few highlights from the study are below.

Assumptions

There were two main assumptions in this click-through rate study:

1. This study used non-branded keywords from only organic (non-paid) search results. Branded keywords come with a bit of bias from the user and a branded search was too easily dominated by one particular brand, so these keywords were omitted from the study.

Methodology

Our research team analyzed the user behavior of more than 170,000 visitors across 624 non-branded keywords (324 were used in the Google sample and 300 in the Bing sample) to generate an accurate click-through rate model. Keywords in the sample set came from a databank of over 10,000 keywords and were chosen based on the strict criteria of a 30-day stable ranking period in the top 10 positions.

Results

Clearly, Google (shown in blue) organic search results have far higher click-throughs on the first page than Bing (shown in green). But where are these Bing users clicking, if not on the organic search results? Possibilities include sidebar "related searches," submitting a new query, selecting a tab at the top, choosing a paid result, or the images, video, news, shopping or local listings, which all appear on page 1 search results.

Does a higher click-through rate mean a higher level of reliability and trust? We cannot be sure, since reliability and trust weren't measured in this click-through rate study. However, there was one very interesting finding in this study: Roughly 117 million searches are made for "Google" in Bing search each month! It's hard to fathom why someone would use one search engine to find another search engine until you analyze the packaging of Microsoft products. Internet Explorer, still the world's most popular Web browser, comes with Bing built-in as the default search engine. Windows 8 also has many built-in uses of Bing, as well as the Xbox 360, and probably many other Microsoft products. While it's true that Firefox and other browsers come with Google as the built-in search engine, our research team was unable to find a significant number of searches for "Bing" in Google search.

Even though Google search holds a bigger reward for inbound marketers than Bing today, it's important to note the growth of Bing search share and their raw determination to stay in the search market. While the majority of your efforts today should be geared towards optimizing for Google results, I still like Bing as a long-term play that can position your brand to the front of the table when Bing's market share grows more significantly in the future.